You will soon need additional documentation to travel to most European countries
 

Starting next year, you will need additional documentation if you travel to most European countries.

You will need an Electronic Travel Authorization to get into the UK and to get into most of the other countries you will need a European Travel Information and Authorization System authorization.

ETIAS - European Union

The U.K. will require electronic travel authorization starting Jan. 8: Travel Weekly

New Zealand and Australia have been doing it for years. I'm surprised Europe has lagged behind. They say it's for security, but I suspect it's also a money maker.
I know for a fact it's going to be a nightmare of long line coming into France the first time. They were supposed to have started it already but the logistics were bringing them down. You'll have to go through this every three years, if I recall correctly.

Same as ESTA visa for us foreigners to enter US.
$21 every two years these days.

No fee for those over 70.